Promotion of the Hypocrellin Yield by a Co-Culture of Shiraia bambusicola (GDMCC 60438) with Arthrinium sp. AF-5 Fungus

Hypocrellin is a natural 3,10-xylene-4,9-anthracene derivative compound that originates from the stroma of Shiraia bambusicola (S. bambusicola) and Hypocrella bambusae with excellent photobiological activities. Submerged fermentation with the mycelia of S. bambusicola is generally regarded as an ideal technology for hypocrellin production. This study developed a co-cultivation strategy for an obvious promotion of the hypocrellin yield by incubating S. bambusicola (GDMCC 60438) with the endophyte fungus Arthrinium sp. AF-5 isolated from the bamboo tissue. The results indicated that the yield of hypocrellin A (HA) reached a 66.75 mg/g carbon source after an 84-h co-cultivation of the two strains, which was a four-time increase of that by the fermentation only with the S. bambusicola. The microscope observation found that the mycelia of the two strains were intertwined with each other to form the mycelium pellets during the co-cultivation. Moreover, the mycelium pellets of the co-culture showed a contracted and slightly damaged morphology. The addition of H2O2 in the fermentation media could further increase the HA production by 18.31%.

Nitric oxide regulates perylenequinones biosynthesis in Shiraia bambusicola S4201 induced by hydrogen peroxide

Shiraia bambusicola has been used as a traditional Chinese medicine for a long history. Its major medicinal active metabolites are perylenequinones, including hypocrellin A, elsinochrome A and so on. At present, the fermentation yield of perylenequinones is low, and its complex biosynthesis and regulatory pathways are still unclear. In this study, nitric oxide, as a downstream signal molecule of hydrogen peroxide, regulates the biosynthesis of perylenequinones. Exogenous addition of 0.01 mM sodium nitroprusside (nitric oxide donor) can promote perylenequinones production by 156% compared with the control. Further research found that hydrogen peroxide and nitric oxide increased the transcriptional level of the biosynthetic genes of hypocrellin A. The results showed that nitric oxide is involved in the biosynthesis and regulation of perylenequinones in Shiraia bambusicola as a signal molecule. In the future, the yield of perylenequinones can be increased by adding exogenous nitric oxide in fermentation.